Discuss how to set dns in golang (a brief analysis of the method)

In Golang, setting DNS is a very common requirement. In this article, we will discuss how to set up DNS for use in Golang.

DNS (Domain Name System) is a distributed database system used to resolve domain names into IP addresses. By default, Golang uses the DNS server provided by the operating system. This is usually a local DNS server, but may also be a remote DNS server. But if you want to use a different DNS server, or if you have other restrictions in your network, you'll need to modify the default settings.

Here's how to set up DNS in Golang:

1. Using net.Resolver
   The net.Resolver type in the Golang standard library provides a convenient interface to query domain names. You can use this to set up DNS servers. The following is sample code for setting up Google's DNS server using net.Resolver:

package main

import (
    "context"
    "fmt"
    "net"
    "time"
)

func main() {
    //创建一个context对象，用于超时控制
    ctx, cancel := context.WithTimeout(context.Background(), time.Second*10)
    defer cancel()

    //设置Google DNS服务器的地址
    resolver := &net.Resolver{
        PreferGo: true,
        Dial:     func(ctx context.Context, network, address string) (net.Conn, error) {
            d := net.Dialer{}
            return d.DialContext(ctx, "udp", "8.8.8.8:53")
        },
    }

    //解析域名
    ips, err := resolver.LookupIPAddr(ctx, "google.com")
    if err != nil {
        panic(err)
    }

    //打印解析结果
    for _, ip := range ips {
        fmt.Println(ip.IP)
    }
}

In the above code, we create a net.Resolver object and set its Dial method to connect to Google DNS server. We then use it to resolve the google.com domain name and print a list of its IP addresses.

2. Using Dialer
   Another way to set up a DNS server is to use the net.Dialer type. The following is a sample code:

package main

import (
    "fmt"
    "net"
    "time"
)

func main() {
    //创建一个默认的Dialer对象
    dialer := net.Dialer{
        Timeout:   time.Second * 10,
        KeepAlive: time.Second * 60,
    }

    //使用Dialer对象连接Google DNS服务器
    conn, err := dialer.Dial("udp", "8.8.8.8:53")
    if err != nil {
        panic(err)
    }
    defer conn.Close()

    //使用连接发送DNS请求
    //这里略过
    //...

    //打印响应结果
    //这里略过
    //...
}

In the above code, we create a net.Dialer object and set its Timeout and KeepAlive properties. We then use this object to connect to Google's DNS servers and send DNS requests. Please note that this only includes code related to connecting and sending requests. In fact, you need to implement the response processing part of the DNS protocol yourself.

Summary

Setting up a DNS server is a very common requirement, and Golang provides a variety of methods to achieve it. You can use the net.Resolver object, or you can use the net.Dialer object. No matter which method you use, you should have appropriate error handling and timeout control to protect your program from network failures and attacks.

The above is the detailed content of Discuss how to set dns in golang (a brief analysis of the method). For more information, please follow other related articles on the PHP Chinese website!